The present disclosure relates to storage management, and more specifically, to storage capacity usage management method and system for a storage system of a plurality of logical storage arrays with a shared storage controller.
Generally, a storage system may comprise a plurality of logical storage arrays arranged in the same pool or across different pools and backed by arrays of physical or tangible storage devices. A storage controller bridges the logical storage arrays with the physical storage devices by performing address transformation and capacity management. Server applications write/read data to/from the logical storage arrays. In the underlying layer, the write/read operations are re-directed to specific addresses in the tangible storage devices by the storage controller.
A storage controller may be shared by two or more logical storage arrays by providing a shared physical capacity in the backend storage devices to the two or more logical storage arrays. In some cases, logical storage arrays may have large logical capacities claimed from the storage controller, but the storage controller actually reserves or allocates small physical capacities on the physical storage devices for the logical arrays to improve storage capacity utilization efficiency. Thin provisioning (TP) is one of such storage mechanisms. Thin provisioning, also referred to as over-allocation or over-subscription, is a virtualized storage mechanism for automatically optimizing storage capacity utilization efficiency. Thin provisioning allows flexible, dynamic and sequential allocation of storage space to server applications on a just-enough, just-in-time and on-demand basis.